What is Fasted Cardio & Why It’s A Big Deal (Beginner’s Guide)

What if I told you that one of the best ways to lose fat quickly is to work out first thing in the morning prior to any food consumption?

This is referred to as fasted cardio, a popular weight-loss approach in the world of fitness.

Many support that it helps accelerate fat loss and help achieve a lean, strong body quicker than regular cardio.

Studies support the ideas that performing physical activity while fasted can result in the body burning fat as a source of energy, meaning fast weight loss.

Kind of makes sense if we think of our ancestors, right?

The norm for them was to wake up and immediately go hunt and gather their food… aka exercising to precede the initial consumption of nutrients.

Let’s take a more in-depth view of this type of training and its benefits.

First Things First: What is Fasted Cardio?

It refers to cardio done in a “fasted” state.

Many people interpret this as cardio done on an “empty stomach.” That is not the case. There is a difference between your stomach feeling empty and full versus it being fed and fasted.

When you consume food, your body breaks it down into various molecules that can be used by the cells and are released into the blood.

Insulin, a hormone produced by the pancreas, is then released, and its function is to move these molecules into other cells around the body.

Depending on the size and makeup of your meal, insulin levels can stay elevated for anywhere between 3 – 6+ hours. [1]

When exercise is being done during a period where insulin levels are higher, and there is food being absorbed and processed, this is called “fed” training.

Therefore, any exercise that is done when insulin levels are at a baseline level, and the food is no longer being absorbed; this is “fasted” training.

When your body is looking for fuel, it will burn whatever you have eaten before it will find alternate sources.

So, if you don’t have any fuel in your stomach because you’re in a fasted state, it will rely on what it has stored away as a form of energy (i.e. fat).

How Does Fasted Cardio Work?

In order for this cardio approach to be most effective, you want to make sure your body continues to burn fat without burning through carbs instead.

By keeping a lower intensity, such as a 30-minute walk or a slow pace Stairmaster, your body can stay within a state that it can melt away fat as a fuel source.

But slow and steady doesn’t necessarily win the race.

Low-intensity cardio will only burn fat during the workout, whereas higher intensity workouts will continue to shed fat after the session as well, the problem however is during the workout, you will burn some fat.

But you end up using stored carbohydrates as a main source of energy.

Many researchers find that incorporating high-intensity interval training (HIIT) while in a fasted state will boost your metabolism and keeps burning fat for extended periods post-workout.

It has also shown to improve insulin sensitivity and overall cardiovascular health. [2]

However, none of this matters if your diet is not in check.

Regardless of the fact that your body is fasted or not, at the end of the day, you only lose weight as a result of a calorie (or energy) deficiency – you must burn more than you eat.

Benefits of Fasted Cardio on Those Stubborn Fat Areas

This is one of the main reasons people turn to fasted cardio.

Its ability to help blast those hard to target fat loss areas. Without getting into the crazy science behind it, the body produces chemicals referred to as catecholamines.

These chemicals break down fat cells so they can be used as energy. [3]

They travel through the blood and attach to fat cell receptors, which triggers the release of energy from within the cells.

They contain two different receptors, beta-receptors and alpha receptors. Beta speeds up the metabolizing of fat and alpha hinders it. [4]

The more alpha receptors a fat cell contains, the more resistant it is to being mobilized. Areas that can get lean quickly have beta-receptor heavy fat cells compared to those that do not.

Blood flow is another huge factor when it comes to shedding stubborn fat areas.

Now, when you do cardio in a fasted state it increases blood flow, particularly in the abdominal region. [5]

This means more catecholamines can travel throughout the body and aid with the mobilization of fat.

It has been found that those who participate in fasted cardio have resulted in a 28% increase of GLUT4, a glucose transponder that allows glucose to be used for energy by the muscles instead of being stored as fat.